Four low order bi-directional three-state data bus lines.Used for data transfer between the MPU and the LCM.These four are not used during 4-bit operation.

11~14

DB4~DB7

MPU

Four high order bi-directional three-state data bus lines.Used for data transfer between the MPU

15

LED+

LED BKL power supply

Power supply for BKL (+4.2V)

16

LED-

Power supply for BKL (GND)

Optical characteristics

STN type display module (Ta=25℃, VDD=5.0V)

Item

Symbol

Condition

Min.

Typ.

Max.

Unit

Viewing angle

θ

Cr≥2

-60

-

35

deg

Φ

-40

-

40

Contrast ratio

Cr

-

6

-

-

Response time (rise)

Tr

-

-

150

250

ms

Response time (fall)

Tr

-

-

150

250

Electrical characteristics

DC characteristics

Parameter

Symbol

Conditions

Min.

Typ.

Max.

Unit

Supply voltage for LCD

V0-Vss

Ta =25℃ V=+5V

-

6.5

-

V

Input voltage

VDD

V=+3.3V

2.7

3.3

5.5

V=+5V

4.7

5.0

5.5

Supply current

IDD

Ta=25℃, VDD=5.0V

-

2

4

mA

Input leakage current

ILKG

-

-

1.0

uA

“H” level input voltage

VIH

2.2

-

VDD

V

“L” level input voltage

VIL

Twice initial value or less

0

-

0.6

“H” level output voltage

VOH

LOH=-0.25mA

2.4

-

-

“L” level output voltage

VOL

LOH=1.6mA

-

-

0.4

Backlight supply voltage

VF

-

4.2

4.6

SERIAL LCD MODULES

Our serial displays are standard sized character LCD modules integrated with RS232, I2C and SPI serial interfaces. With this type of display, there are no more additional bulky “daughter boards” which results in better usability and cost. Software controlled contrast and backlight brightness simplifies development and maximizes application performance.

FAQ

1. When are SPI interfaces used ?

SPI interfaces are used when the micro-controller has to transmit data to a device without an internal clock. This is precisely the situation that occurs when we use the MicroStamp11 to transmit data to the shift-register. The MicroStamp11 has an internal clock, but the shift-register has no clock. We usually think of the device with the clock as a master and the other device as a slave.

2.What is COB LCD modules?

COB (Chip-On-Board) LCD modules are passive-matrix displays designed with a pcb, where the controller IC or driver is directly mounted on the back of the PCB, and the PCB is affixed to the LCD glass. The COB mounting method allows for easy assembly of the display to any design application.

3.ST7920 LCD controller/driver IC can display alphabets, numbers, Chinese fonts and self-defined characters. It supports 3 kinds of bus interface, namely 8 bit/ 4bit and serial. All functions, including display RAM, character generator ROM, LCD display drivers and control circuits are all in a one-chip solution.